Allow @psalm-assert to propagate member assertions to the caller's context (#2100)

This change injects method call assertions that involve member variables
to the caller context by replacing `$this->` with the lhs of the member
call.

Fixes: #2099

src/Psalm/Internal/Analyzer/Statements/Expression/Call/FunctionCallAnalyzer.php

@@ -670,6 +670,7 @@ class FunctionCallAnalyzer extends \Psalm\Internal\Analyzer\Statements\Expressio
             if ($function_storage->assertions && $stmt->name instanceof PhpParser\Node\Name) {
                 self::applyAssertionsToContext(
                     $stmt->name,
+                    null,
                     $function_storage->assertions,
                     $stmt->args,
                     $generic_params ?: [],

src/Psalm/Internal/Analyzer/Statements/Expression/Call/MethodCallAnalyzer.php

@@ -39,11 +39,13 @@ use Psalm\Type\Atomic\TNamedObject;
 use function is_string;
 use function array_values;
 use function array_shift;
+use function array_unshift;
 use function get_class;
 use function strtolower;
 use function array_map;
 use function array_merge;
 use function explode;
+use function implode;
 use function array_search;
 use function array_keys;
 use function in_array;
@@ -1306,6 +1308,7 @@ class MethodCallAnalyzer extends \Psalm\Internal\Analyzer\Statements\Expression\
                         if ($method_storage->assertions) {
                             self::applyAssertionsToContext(
                                 $stmt->name,
+                                ExpressionAnalyzer::getArrayVarId($stmt->var, null, $statements_analyzer),
                                 $method_storage->assertions,
                                 $args,
                                 $class_template_params ?: [],

src/Psalm/Internal/Analyzer/Statements/Expression/Call/StaticCallAnalyzer.php

@@ -905,6 +905,7 @@ class StaticCallAnalyzer extends \Psalm\Internal\Analyzer\Statements\Expression\
                     if ($method_storage->assertions) {
                         self::applyAssertionsToContext(
                             $stmt->name,
+                            null,
                             $method_storage->assertions,
                             $stmt->args,
                             $found_generic_params ?: [],

src/Psalm/Internal/Analyzer/Statements/Expression/CallAnalyzer.php

@@ -50,10 +50,12 @@ use function count;
 use function in_array;
 use function array_reverse;
 use function array_filter;
+use function is_null;
 use function is_string;
 use function assert;
 use function preg_match;
 use function preg_replace;
+use function str_replace;
 use function is_int;
 use function substr;
 use function array_merge;
@@ -3187,6 +3189,7 @@ class CallAnalyzer
     /**
      * @param PhpParser\Node\Identifier|PhpParser\Node\Name $expr
      * @param  \Psalm\Storage\Assertion[] $assertions
+     * @param  string $thisName
      * @param  array<int, PhpParser\Node\Arg> $args
      * @param  Context           $context
      * @param  array<string, array<string, array{Type\Union}>> $template_type_map,
@@ -3196,6 +3199,7 @@ class CallAnalyzer
      */
     protected static function applyAssertionsToContext(
         $expr,
+        ?string $thisName,
         array $assertions,
         array $args,
         array $template_type_map,
@@ -3225,6 +3229,8 @@ class CallAnalyzer
                 }
             } elseif (isset($context->vars_in_scope[$assertion->var_id])) {
                 $assertion_var_id = $assertion->var_id;
+            } elseif (strpos($assertion->var_id, '$this->') === 0 && !is_null($thisName)) {
+                $assertion_var_id = $thisName . str_replace('$this->', '->', $assertion->var_id);
             }
 
             if ($assertion_var_id) {

tests/AssertTest.php

@@ -685,6 +685,32 @@ class AssertTest extends TestCase
                         }
                     }'
             ],
+            'assertPropertyVisibleOutside' => [
+                '<?php
+                    class A {
+                        public ?int $x = null;
+
+                        public function maybeAssignX() : void {
+                            if (rand(0, 0) == 0) {
+                                $this->x = 0;
+                            }
+                        }
+
+                        /**
+                         * @psalm-assert !null $this->x
+                         */
+                        public function assertProperty() : void {
+                            if (is_null($this->x)) {
+                                throw new RuntimeException();
+                            }
+                        }
+                    }
+
+                    $a = new A();
+                    $a->maybeAssignX();
+                    $a->assertProperty();
+                    echo (2 * $a->x);',
+            ],
         ];
     }